This invention relates to photographic systems, and particularly to cameras with flash units capable of operating in different photographic modes.
Ordinary photographic devices are generally capable of operating in a "daylight" mode in which the photograph is taken with ambient light alone and in an "auxiliary light" or "flash" mode in which a photograph is taken on the basis of light from a flash or on the basis of daylight and auxiliary light.
Furthermore, cameras themselves can perform in daylight in a number of modes. For example a camera may operate in a shutter speed priority mode, according to which the shutter speed is manually dialed and the camera automatically adjusts the diaphragm to an aperture appropriate for the shutter speed, the brightness of the scene, and the object being photographed. A camera may also function in an aperture priority mode, in which a photographer enters a desired aperture value and the camera automatically adjusts the shutter speed to the established aperture and other conditions.
Therefore, a photographer must decide in advance upon a photographic mode and adjust each of the components of a photographic system accordingly. In conventional photographic systems, it is necessary, for selecting the mode, to combine mechanical and electrical switches. This complicates photographic devices and exposes them to damage. Furthermore, electronic switching is susceptible to fluctuations of the voltage source which can result in misoperation.
An object of the invention is to improve photographic devices.
Another object of the invention is to eliminate the aforementioned shortcomings.
Another object of the invention is to permit mode selection despite the effect of fluctuating source voltages and variation in the output of the camera's battery with age.
Another object of the invention is to furnish a separate flash unit which requires a minimum number of connections to the camera and in which the mode is selected with a minimum number of connections.